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STEP 1 > Biochem > Flashcards

Biochem Flashcards

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1
Q

I Cell Disease

A
  • Inherited lysosomal storage disease
  • Defect in N-acetylglucosaminyl-1-phosphotransferase, failure of Golgi to phosphorylate mannose residues (↓ mannose-6-phosphate)
  • Proteins secreted extracellularly instead of delivered to lysosomes
  • Coarse facial features, clouded corneas, restricted joint movement, high plasma levels of lysosomal enzymes
  • Often fatal in childhood
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2
Q

Zellweger syndrome

A
  • Peroxisomal disorder (deficit in synthesis of plasmalogens)
  • Hypotonia, Seizures, Hepatomegaly, early death
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3
Q

Refsum Disease

A
  • Peroxisomal disorder
  • Scaly skin, ataxia, cataracts/night blindness, shortening of 4th toe, epiphyseal dysplasia
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4
Q

Prader-Willi Syndrome

A
  • Maternal imprinting, Paternal gene is deleted/mutated
  • Hyperphagia, obesity, intellectual disability, hypogonadism, hypotonia
  • 25% due to maternal uniparental disomy
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5
Q

Angelman syndrome

A
  • Paternal imprinting (paternal gene normally silent), maternal gene is deleted/mutated
  • Inappropriate laughter (“happy puppet”), seizures, ataxia, and severe intellectual disability
  • 5% due to paternal uniparental disomy
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6
Q

Fragile X Syndrome

A
  • X-linked Dominant, trinucleotide repeat in FMR1 gene (CGG), hypermethylation & decreased expression
  • Most common cause of inherited intellectual disability and autism
  • Macroorchidism, long face, large jaw, large everted ears, autism, mitral valve prolapse
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7
Q

Edwards Syndrome

A
  • Trisomy 18
  • Prominent occiput, rocker-bottom feet, Intellectual disability, Nondisjunction, Clenched fists, low-set Ears, micrognathia, congenital heart disease
  • Death by age 1
  • ↓β-hCG, ↓α-fetoprotein, ↓estriol, ↓ or normal inhibin A
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8
Q

Patau Syndrome

A
  • Trisomy 13
  • Severe intellectual disability, Rocker-bottom feet, micropthalmia, microcephaly, cleft liP/Palate, holoProsencephaly, Polydactyly, cutis aPlasia, congenital heart disease
  • Death by age 1
  • ↓βhCG, ↓PAPP-A
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9
Q

Cri-du-Chat Syndrome

A
  • Congenital deletion on short arm of chromosome 5
  • Microcephaly, moderate to severe intellectual disability, high-pitched crying/meowing, epicanthal folds, cardiac abnormalities (VSD)
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10
Q

Williams Syndrome

A
  • Congenital microdeletion of long arm of chromosome 7 (deleted region includes elastin gene)
  • Elfin facies, intellectual disability, hypercalcemia (increased Vit D sensitivity), well-developed verbal skills, extreme friendliness with strangers, cardiovascular problems
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11
Q

Thiamine is a cofactor for what enz?

A
  • Pyruvate Dehydrogenase (links glycolysis to TCA)
  • α-ketoglutarate dehydrogenase (TCA)
  • Transketolase (HMP shunt)
  • Branched-chain ketoacid dehydrogenase
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12
Q

B2 is cofactor for what enz?

A
  • Succinate dehydrogenase (FAD and FMN)
  • Complex II in electron transport chain
  • Deficiency: Cheilosis, Corneal vascularization
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13
Q

B7 is cofactor for what enz?

A

Cofactor for carboxylation enzymes

  • Pyruvate carboxylase (pyruvate → oxaloacetate)
  • Acetyl-CoA carboxylase (acetyl CoA → malonyl CoA)
  • Propionyl-CoA carboxylase (propionyl-CoA → methylmalonyl-CoA)
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14
Q

CYP Inducers

A
  • Carbamazepine
  • Barbiturates
  • Phenytoin
  • Rifampin
  • Griseofulvin St John’s wort
  • Modafinil
  • Cyclophosphamide
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15
Q

CYP Inhibitors?

A
  • Amiodarone
  • Cimetidine
  • Fluoroquinolones
  • Clarithromycin
  • Azole antifungals
  • Grapefruit juice
  • Isoniazid
  • Ritonavir (protease inhibitors)
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16
Q

Pyruvate Dehydrogenase Deficiency

A
  • Buildup of pyruvate that gets shunted to lactate (via LDH) and alanine (via ALT)
  • X-linked
  • Neurologic deficits, lactic acidosis, increased serum alanine
  • Treat: Ketogenic nutrients (fat, lysine, leucine)
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17
Q

Essential Fructosuria

A
  • Defect in fructokinase
  • AR, benign, asymptomatic
  • Fructose appears in blood & urine
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18
Q

Hereditary Fructose Intolerance

A
  • Deficiency of aldolase B
  • AR
  • Fructose-1-phosphate accumulates causing decrease in available phosphate. Inhibition of glycogenolysis and gluconeogenesis.
  • Sx follow consuming fruit, juice or honey
  • Urine dipstick neg (no glucose), Reducing sugars in urine
  • Hypoglycemia, Jaundice, Cirrhosis, Vomiting
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19
Q

Galactokinase Deficiency

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A
  • Deficiency of galactokinase
  • Galactitol accumulates, mild, AR
  • Galactosemia, Galactosuria
  • Infantile cataracts, failure to track objects or develop social smile
20
Q

Classic Galactosemia

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A
  • Absence of galactose-1-phosphate uridyltransferase
  • AR
  • Sx begin with feeding
  • Failure to thrive, jaundice, hepatomegaly, infantile cataracts (galactitol), intellectual disability, E coli sepsis
21
Q

Ornithine Transcarbamylase Deficiency

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A
  • X linked recessive
  • Evident infirst few days of life
  • Excess carbamoyl phosphate converted to orotic acid (part of pyrimidine synthesis pathway)
  • Increased orotic acid in blood and urine, less BUN, hyperammonemia
  • NO MEGALOBLASTIC ANEMIA (vs. orotic aciduria)
22
Q

Phenylketonuria

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A
  • ↓Phenylalanine hydroxylase or ↓BH4
  • Tyrosine becomes essential, ↑ Phenylalanine
  • Intellectual disability, growth retardation, seizures, fair skin, eczema, musty body odor
  • Treat: ↑ dietary Tyrosine, ↓ phenylalanine, avoid aspartame (containe Phe)
  • Maternal PKU - microcephaly, intellectual disability, growth retardation, heart defects
23
Q

Maple Syrup Urine DIsease

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A
  • AR, Blocked degradation of branched amino acids (Isoleucine, Leucine, Valine)
  • ↓ branched-chain α-ketoacid dehydrogenase (B1)
  • CNS defects, intellectual disability, death, poor feeding, vomiting, urine smells like maple syrup
24
Q

Alkaptonuria

Study These Flashcards
A
  • Congenital deficiency of homogentisate oxidase in the degradative pathway of tyrosine to fumarate (pigment forming homogentisic acid accumulates)
  • AR, usually benign
  • Blue-black connective tissue, cartilage, and sclerae
  • Urine turns black on standing
  • Arthralgias (toxic to cartilage)
  • Treat: Restrict dietary Phe & Tyr
25
Homocystinuria
* Cystathione Synthase Deficiency * ↓ Affinity of Cystathione cynthase for pyridoxal phosphate * Methione synthase deficiency * **Excess homocysteine in urine**, osteoporosis, **marfanoid habitus**, ocular changes (downward & inward subluxation), **cardiovascular effects,** kyphosis, **intellectual disability**
26
Von Gierke disease
* Type I Glycogen storage disease * Deficient **Glucose-6-phosphatase** (in liver) * Severe fasting hypoglycemia, ↑↑ Glycogen in liver, ↑ blood lactate, ↑ triglycerides, ↑ uric acid (Gout) and hepatomegaly * _Treat_: frequent oral glucose/cornstarch, avoid fructose & galactose
27
Pompe disease
* Type II Glycogen storage disease * Deficient **α-1,4-glucosidase** * **Cardiomegaly**, hypertrophic cardiomyopathy, hypotonia, exercise intolerance, early death, large tongue * **"P**om**P**e trasher the **P**um**P****"** (1,4)
28
Cori disease
* Type III Glucogen storage disease * Deficient **Debranching enzyme** (α-1,6-glucosidase) * Milder form of von Gierke w/ **normal blood lactate levels**, accumulation of limit dextran-like structures in cytosol (muscle involvement, milder hypoglyceia) * Gluconeogenesis in tact
29
McArdle Disease
* Type IV Glycogen Storage Disease (AR) * Deficient **skeletal muscle glycogen phosphorylase** (Myophosphorylase) * ↑ Glycogen in muscle but muscle cannot break it down, painful **muscle cramps**, **myoglobinuria** with strenuous exercise, arrhythmia from electrolyte abnormalities * Second wind phenomenon during exercise due to increased musculra blood flow * **Normal blood glucose** * **M**cardle = **M**uscle
30
Tay Sachs
* AR Lysosomal storage disease * _Deficient_: Hexosaminidase A * _Accumulated_: GM2 Ganglioside * _Sx_: Progressive neurodegeneration, developmental delay, "cherry-red" spot on macula, no HSM (vs. Niemann-Pick)
31
Fabry disease
* XR Lysosomal storage Disease * _Deficient_: α-galactosidase A * _Accumulated_: Ceramide trihexoside * Peripheral neuropathy, angiokeratomas, hypohidrosis (Late - progressive renal failure, cardiovascular disease)
32
Metachromatic Leukodystrophy
* AR Lysosomal storage disease * _Deficient_: Arylsulfatase A * _Accumulated_: Cerebroside sulfate * Central and peripheral demyelination with ataxia, dementia
33
Krabbe disease
* AR lysosomal storage disease * _Deficient_: Galactocerebrosidase * _Accumulated_: Galactocerebroside, psychosine * Peripheral neuropathy, destruction of oligodendrocytes, developmental delay, optic atrophy, globoid cells
34
Gaucher Disease
* AR Lysosomal storage disease * _Deficient_: Glucocerebrosidase * _Accumulated_: Glucocerebroside * Most common LSD, **hepatosplenomegaly,** pancytopenia, osteoporosis, avascular necrosis of femur, bone crises, Gaucher cells (lipid laden macrophages resembling **crumpled tissue paper**)
35
Niemann-Pick disease
* AR Lysosomal storage disease * _Deficient_: Sphingomyelinase * _Accumulated_: Sphingomyelin * Progressive neurodegeneration, **hepatosplenomegaly**, foam cells, "cherry red" spot on the macula
36
Hurler syndrome
* AR lysosomal stroage disease (mucopolysaccharidoses) * _Deficient_: α-L-iduronidase * _Accumulated_: Heparan sulfate, dermatan sulfate * Developmental delay, gargoylism, airway obstruction, **corneal clouding**, hepatosplenomegaly
37
Hunter Syndrome
* **XR** Lysosomal storage disease (Mucopolysaccharidoses) * _Deficient_: Iduronate 2 sulfatase * _Accumulated_: Heparan sulfate, dermatan sulfate * Mild Hurler + aggressive behavior (no corneal clouding)
38
Systemic Primary Carnitine Deficiency
* Inherited deficiency in transport of LCFAs into the mitochondria, toxic accumulation * Weakness, hypotonia, and **hypoketotic hypoglycemia**
39
Mediam Chain Acyl-CoA Dehydrogenase deficiency
* Decreased ability to break down fatty acids into acetyl-CoA * Accumulation of fatty acyl carnitines in the blood w/ **hypoketotic hypoglycemia** * Causes vomiting, lethargy, seizures, coma, liver dysfunction (can lead to sudden death in infants/children) * Treat by AVOIDING FASTING
40
Abetalipoproteinemia
* AR - absent chylomicrons, VLDL, LDL * Deficiency in ApoB48, ApoB100 * Infants present w/ severe fat malabsorption, steatorrhea, failure to thrive * Later manifestations - retinitis pigmentosa, spinocerebellar degeneration (deficient vit E), ataxia, acantholysis * _Treat_: restrict long-chain fatty acids, oral vitamin E
41
Hyperchylomicronemia
* AR deficiency of **lipoprotein lipase** or **apolipoprotein C-II** * Increased chylomicrons, TG, cholesterol * Pancreatitis, hepatosplenomegaly, eruptive/pruritic xanthomas (no ↑ atherosclerosis risk) * Creamy layer in supernatant
42
Familial Hypercholesterolemia
* AD, absent or defective LDL receptors * Incerased blood LDL, cholesterol, (sometimes VLDL) * Accelerated atherosclerosis (early MI), tendon xanthomas, corneal arcus * Heterozygotes = 300, Homozygotes 700+
43
Dysbetalipoproteinemia
* AR, defective Apo E (can't clear remnants) * Increased chylomicrons, VLDL * Premature atherosclerosis, tuberoeruptive xanthomas, xanthoma striatum palmare
44
Hypertriglyceridemia
* AD, hepatic overproduction of VLDL * Increased VLDL, TG * **Hypertriglyceridemia (\>1000) can cause acute pancreatitis**
45
What parts of metabolism occur in mitochondria?
* Fatty acid oxidation (β-oxidation) * Acetyl-CoA production * TCA cycle * Oxidative phosphorylation * Ketogenesis * **H**eme synthesis, **U**rea cycle, **G**luconeogenesis are in BOTH mito & cytoplasm ("hugs take two")
46
What parts of metabolism are in the cytoplasm?
* Glycolysis * HMP shunt * Synthesis of steroids (SER) * Proteins (ribosomes, RER) * Fatty acids * Cholesterol * Nucleotides * **H**eme synthesis, **U**rea cycle, **G**luconeogenesis ("Hugs take two")

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